1. Field of the Invention
This invention relates to electrical connectors and more particularly to an electrical connector for coupling an integrated circuit package to a backpanel.
2. Description of the Prior Art
The need for an improved integrated circuit interconnection technique has become critical from performance and profit standpoints, with companies who are trying to use the highly developed microelectronic integrated circuit technology in commercial and consumer applications such as computers, automotive, appliances, communications, industrial components, industrial systems and the like.
This problem stems from the increased packaging densities of the microelectronic integrated circuit packages which require more electrical contacts to couple input-output signals to the integrated circuit chips within the packages. The connectors for physcially mounting the integrated circuited packages and electrically interconnecting them into the system in which they are to be used oftentimes are larger and occupy more valuable space than the packages themselves.
Integrated circuit packages of the well known daul-in-line package type (DIP), is a rectangular body with leads extending from opposite longitudinal edges thereof, and such structures have several problems and shortcomings with regard to their extending leads and limitations of contact spacing. The leads of the DIP are not strong enough for the manual and mechanical handling which they are receiving as they are being employed in the various applications. Further, since the leads of the DIP are located only on two opposite side edges of the package, the contact spacing is seriously limited. The lead strength problem of the DIP has led to the development of what is referred to as a leadless dual-in-line package, in which terminal pads are provided in place of the extending leads. While this solved the lead strength problem, it did not solve the problem of the lack of contact space.
To solve the problem of contact space, an integrated circuit package of square configuration with contacts on all four side edges thereof was developed. These packages, which are sometimes referred to as JEDEC large scale integrated circuit packages, are usually multichip carriers having common contact patterns on all edges thereof, and are fabricated as both leaded and leadless structures.
Commercial acceptance of these new packages, i.e., DIP leadless and JEDEC leaded and leadless, has been relatively slow for several reasons, with a particular problem stemming from the connectors for mounting and electrically interconnecting packages with a backpanel such as a printed circuit board or wiring panel.
Various connector configurations have been employed or suggested for the various integrated circuit packages, with these prior art connectors being relatively costly, bulky, and multipart complex structures. Since the use of terminal pads in the leadless structures dictates that a pressure type of interconnection be employed, the forces needed to achieve reliable connections becomes quite large and can be a serious problem when relatively large numbers of such interconnections are to be made.
One particular prior art connector employs a base which is mounted on the backpanel by soldering or otherwise attaching the wire wrap pins, which depend from the base, into the backpanel. The leadless package is mounted within a recess provided in the base and the terminal pads of the package are pressurized into conductive contact with upwardly extending portions of the wire wrap pins. The necessary downward pressure is accomplished by means of a cover hingedly mounted on the base. This, and similar prior art connectors, are usually employed only on relatively small leadless packages of the type having terminal pads on only two edges thereof due to the inability of such covers to achieve equal pressurization over long spans and on packages having terminal pads on more than two edges.
Another type of prior art connector employs a base, similar to the one described above, for receiving the leadless package. A force exerting element is placed on the leadless package and is pressurized downwardly by means of a cover which is screwed in place. The screws are located only at the corners or ends of such connectors, as determined by the geometric configuration, so as not to sacrifice valuable contact space. Such a mounting technique complicates the servicing and when relatively large leadless packages are mounted in this type of connector, uneven contact pressurization can result in the spans between the mounting screws due to deflection or bowing of the cover and the force exerting element.
A particular prior art connector, which is fully disclosed in U.S. Pat. No. 3,904,262, issued on Sept. 9, 1975, to the sme inventor, includes a base receptacle mounted on a backpanel and having contact means therein which are in contact with the backpanel. The receptacle is adapted to receive the circuit package therein so that the terminal pads thereof are in alignment with the contact means provided in the receptacle. A cover is removably mounted in the receptacle and is laterally slidable relative thereto into and out of engagement with inclined plane members formed in the receptacle. When the cover is moved into engagement with the inclined plane members, it will be deflected down and locked in place to load the terminal pads of the circuit package into conductive contact with the contact means of the base receptacle. This connector, while constituting a substantial improvement in the art has some drawbacks in that the wedging action provided by engagement of the cover with the inclined plane members is exerted only on three sides of the circuit package thus making it possible for unequal pressurization of the terminal pads on the fourth side of the circuit package to occur. Further, this prior art connector requires the use of tooling to accomplish the required lateral sliding of the cover thereof.
In view of the foregoing, a need exists for a new and improved connector for integrated circuit packages which overcomes some of the problems and shortcomings of the prior art.